Competition would include Amazon’s Echo, Alphabet’s Google Home and coming entries from Apple and Microsoft

SEOUL—Samsung Electronics Co. is developing a voice-activated speaker powered by its digital assistant Bixby, according to people familiar with the matter, joining a proliferating arms race in tabletop devices.

The timing is far from determined, the people said. The English-language version of Bixby has been delayed and they said many of the speaker’s features and other specifications are yet to be decided. But the project—internally code-named “Vega”—has been going on for more than a year, several of the people said.